Transfer lamination of electrodes in silicon-dominant anode cells

ABSTRACT

Systems and methods are provided for high volume roll-to-roll transfer lamination of electrodes for silicon-dominant anode cells.

CLAIM OF PRIORITY

This patent application is a continuation of U.S. patent applicationSer. No. 16/681,641, filed on Nov. 12, 2019, which in turn makesreference to, claims priority to and claims benefit from U.S.Provisional Patent Application Ser. No. 62/854,935, filed on May 30,2019. The above identified application is hereby incorporated herein byreference in its entirety.

TECHNICAL FIELD

Aspects of the present disclosure relate to energy generation andstorage. More specifically, certain implementations of the presentdisclosure relate to methods and systems for transfer lamination ofelectrodes in silicon-dominant anode cells.

BACKGROUND

Various issues may exist with conventional battery technologies. In thisregard, conventional systems and methods, if any existed, for designingand making battery anodes may be costly, cumbersome, and/orinefficient—e.g., they may be complex and/or time consuming toimplement, and may limit battery lifetime.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present disclosureas set forth in the remainder of the present application with referenceto the drawings.

BRIEF SUMMARY

System and methods are provided for transfer lamination of electrodes insilicon-dominant anode cells, substantially as shown in and/or describedin connection with at least one of the figures, as set forth morecompletely in the claims.

These and other advantages, aspects and novel features of the presentdisclosure, as well as details of an illustrated embodiment thereof,will be more fully understood from the following description anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a battery with silicon-dominated anode, inaccordance with an example embodiment of the disclosure.

FIG. 2 illustrates an example silicon-dominant anode, in accordance withan example embodiment of the disclosure.

FIG. 3 is a flow diagram of an alternative process for transferlamination of electrodes, in accordance with an example embodiment ofthe disclosure.

FIG. 4 illustrates roll press and flat press of anode active material,in accordance with an example embodiment of the disclosure.

FIG. 5 illustrates two-sided roll press of anode active material, inaccordance with an example embodiment of the disclosure.

FIG. 6 illustrates an example high volume roll-to-roll electrodelamination based system, in accordance with an example embodiment of thedisclosure.

FIG. 7 illustrates another example high volume roll-to-roll electrodelamination based system, in accordance with an example embodiment of thedisclosure.

FIG. 8 illustrates a top view of an example roll-to-roll system withmultiple manufacturing lanes, in accordance with an example embodimentof the disclosure.

FIG. 9 illustrates a top view of an embodiment of an electrode roll withmultiple mixture strips on a single current collector, in accordancewith an example embodiment of the disclosure.

FIG. 10 is a plot illustrating cycle life performance for cells that useelectrodes produced using high-volume lamination based roll-to-rollprocess, in accordance with an example embodiment of the disclosure.

FIG. 11 is a plot illustrating cell thickness expansion performance forcells that use electrodes produced using high-volume lamination basedroll-to-roll process, in accordance with an example embodiment of thedisclosure.

DETAILED DESCRIPTION

FIG. 1 is a diagram of a battery with silicon-dominated anode, inaccordance with an example embodiment of the disclosure. Referring toFIG. 1, there is shown a battery 100 comprising a separator 103sandwiched between an anode 101 and a cathode 105, with currentcollectors 107A and 107B. There is also shown a load 109 coupled to thebattery 100 illustrating instances when the battery 100 is in dischargemode. In this disclosure, the term “battery” may be used to indicate asingle electrochemical cell, a plurality of electrochemical cells formedinto a module, and/or a plurality of modules formed into a pack.

The development of portable electronic devices and electrification oftransportation drive the need for high performance electrochemicalenergy storage. Small-scale (<100 Wh) to large-scale (>10 KWh) devicesprimarily use lithium-ion (Li-ion) batteries over other rechargeablebattery chemistries due to their high-performance.

The anode 101 and cathode 105, along with the current collectors 107Aand 107B, may comprise the electrodes, which may comprise plates orfilms within, or containing, an electrolyte material, where the platesmay provide a physical barrier for containing the electrolyte as well asa conductive contact to external structures. In other embodiments, theanode/cathode plates are immersed in electrolyte while an outer casingprovides electrolyte containment. The anode 101 and cathode areelectrically coupled to the current collectors 107A and 107B, whichcomprise metal or other conductive material for providing electricalcontact to the electrodes as well as physical support for the activematerial in forming electrodes.

The configuration shown in FIG. 1 illustrates the battery 100 indischarge mode, whereas in a charging configuration, the load 107 may bereplaced with a charger to reverse the process. In one class ofbatteries, the separator 103 is generally a film material, made of anelectrically insulating polymer, for example, that prevents electronsfrom flowing from anode 101 to cathode 105, or vice versa, while beingporous enough to allow ions to pass through the separator 103.Typically, the separator 103, cathode 105, and anode 101 materials areindividually formed into sheets, films, or active material coated foils.Sheets of the cathode, separator and anode are subsequently stacked orrolled with the separator 103 separating the cathode 105 and anode 101to form the battery 100. In some embodiments, the separator 103 is asheet and generally utilizes winding methods and stacking in itsmanufacture. In these methods, the anodes, cathodes, and currentcollectors (e.g., electrodes) may comprise films.

In an example scenario, the battery 100 may comprise a solid, liquid, orgel electrolyte. The separator 103 preferably does not dissolve intypical battery electrolytes such as compositions that may comprise:Ethylene Carbonate (EC), Fluoroethylene Carbonate (FEC), PropyleneCarbonate (PC), Dimethyl Carbonate (DMC), Ethyl Methyl Carbonate (EMC),Diethyl Carbonate (DEC), etc. with dissolved LiBF₄, LiAsF₆, LiPF₆, andLiClO₄ etc. The separator 103 may be wet or soaked with a liquid or gelelectrolyte. In addition, in an example embodiment, the separator 103does not melt below about 100 to 120° C., and exhibits sufficientmechanical properties for battery applications. A battery, in operation,can experience expansion and contraction of the anode and/or thecathode. In an example embodiment, the separator 103 can expand andcontract by at least about 5 to 10% without failing, and may also beflexible.

The separator 103 may be sufficiently porous so that ions can passthrough the separator once wet with, for example, a liquid or gelelectrolyte. Alternatively (or additionally), the separator may absorbthe electrolyte through a gelling or other process even withoutsignificant porosity. The porosity of the separator 103 is alsogenerally not too porous to allow the anode 101 and cathode 105 totransfer electrons through the separator 103.

The anode 101 and cathode 105 comprise electrodes for the battery 100,providing electrical connections to the device for transfer ofelectrical charge in charge and discharge states. The anode 101 maycomprise silicon, carbon, or combinations of these materials, forexample. Typical anode electrodes comprise a carbon material thatincludes a current collector such as a copper sheet. Carbon is oftenused because it has excellent electrochemical properties and is alsoelectrically conductive. Anode electrodes currently used in rechargeablelithium-ion cells typically have a specific capacity of approximately200 milliamp hours per gram. Graphite, the active material used in mostlithium ion battery anodes, has a theoretical energy density of 372milliamp hours per gram (mAh/g). In comparison, silicon has a hightheoretical capacity of 4200 mAh/g. In order to increase volumetric andgravimetric energy density of lithium-ion batteries, silicon may be usedas the active material for the cathode or anode. Silicon anodes may beformed from silicon composites, with more than 50% silicon, for example.

In an example scenario, the anode 101 and cathode 105 store the ion usedfor separation of charge, such as lithium. In this example, theelectrolyte carries positively charged lithium ions from the anode 101to the cathode 105 in discharge mode, as shown in FIG. 1 for example,and vice versa through the separator 105 in charge mode. The movement ofthe lithium ions creates free electrons in the anode 101 which creates acharge at the positive current collector 107B. The electrical currentthen flows from the current collector through the load 109 to thenegative current collector 107A. The separator 103 blocks the flow ofelectrons inside the battery 100, allows the flow of lithium ions, andprevents direct contact between the electrodes.

While the battery 100 is discharging and providing an electric current,the anode 101 releases lithium ions to the cathode 105 via the separator103, generating a flow of electrons from one side to the other via thecoupled load 109. When the battery is being charged, the oppositehappens where lithium ions are released by the cathode 105 and receivedby the anode 101.

The materials selected for the anode 101 and cathode 105 are importantfor the reliability and energy density possible for the battery 100. Theenergy, power, cost, and safety of current Li-ion batteries need to beimproved in order to, for example, compete with internal combustionengine (ICE) technology and allow for the widespread adoption ofelectric vehicles (EVs). High energy density, high power density, andimproved safety of lithium-ion batteries are achieved with thedevelopment of high-capacity and high-voltage cathodes, high-capacityanodes and functionally non-flammable electrolytes with high voltagestability and interfacial compatibility with electrodes. In addition,materials with low toxicity are beneficial as battery materials toreduce process cost and promote consumer safety.

The performance of electrochemical electrodes, while dependent on manyfactors, is largely dependent on the robustness of electrical contactbetween electrode particles, as well as between the current collectorand the electrode particles. The electrical conductivity of siliconanode electrodes may be manipulated by incorporating conductiveadditives with different morphological properties. Carbon black (SuperP), vapor grown carbon fibers (VGCF), and a mixture of the two havepreviously been incorporated separately into the anode electroderesulting in improved performance of the anode. The synergisticinteractions between the two carbon materials may facilitate electricalcontact throughout the large volume changes of the silicon anode duringcharge and discharge.

State-of-the-art lithium-ion batteries typically employ agraphite-dominant anode as an intercalation material for lithium.Silicon-dominant anodes, however, offer improvements compared tographite-dominant Li-ion batteries. Silicon exhibits both highergravimetric (3579 mAh/g vs. 372 mAh/g for graphite) and volumetriccapacities (2194 mAh/L vs. 890 mAh/L for graphite). In addition,silicon-based anodes have a lithiation/delithiation voltage plateau atabout 0.3-0.4V vs. Li/Li⁺, which allows it to maintain an open circuitpotential that avoids undesirable Li plating and dendrite formation.While silicon shows excellent electrochemical activity, achieving astable cycle life for silicon-based anodes is challenging due tosilicon's large volume changes during lithiation and delithiation.Silicon regions may lose electrical contact from the anode as largevolume changes coupled with its low electrical conductivity separate thesilicon from surrounding materials in the anode.

In addition, the large silicon volume changes exacerbate solidelectrolyte interphase (SEI) formation, which can further lead toelectrical isolation and, thus, capacity loss. Expansion and shrinkageof silicon particles upon charge-discharge cycling causes pulverizationof silicon particles, which increases their specific surface area. Asthe silicon surface area changes and increases during cycling, SEIrepeatedly breaks apart and reforms. The SEI thus continually builds uparound the pulverizing silicon regions during cycling into a thickelectronic and ionic insulating layer. This accumulating SEI increasesthe impedance of the electrode and reduces the electrode electrochemicalreactivity, which is detrimental to cycle life.

FIG. 2 illustrates an example silicon-dominant anode, in accordance withan example embodiment of the disclosure. Shown in FIG. 2 are a currentcollector 201, an optional adhesive 203, and an active material 205. Itshould be noted, however, that the adhesive 203 may or may not bepresent depending on the type of anode fabrication process utilized, asthe adhesive is not necessarily present in a direct coating processwhere the active material is formed directly on the current collector.

In an example scenario, the active material 205 before pyrolysiscomprises silicon particles in a binder material and a solvent, theactive material 205 being pyrolyzed to turn the binder into a glassycarbon that provides a structural framework around the silicon particlesand also provides electrical conductivity. The active material may becoupled to the current collector 201 using the optional adhesive 203.The current collector 201 may comprise a metal film, such as copper,nickel, or titanium, for example, although other conductive foils may beutilized depending on desired tensile strength.

FIG. 2 also illustrates lithium particles impinging upon and lithiatingthe active material 205. As illustrated in FIG. 2, the current collector201 has a thickness t, which may vary based on the particularimplementation. In this regard, in some implementations thicker foilsmay be used while in other implementations thinner foils are used.Example thicker foils may be greater than 6 μm, such as 10 μm or 20 μmfor copper, for example, while thinner foils may be less than 6 μm thickin copper

In an example scenario, when an adhesive is used, the adhesive 203comprises a polymer such as polyimide (PI) or polyamide-imide (PAI) thatprovides adhesive strength of the active material film 205 to thecurrent collector 201 while still allowing electrical contact to thecurrent collector 201. Other adhesives may be utilized depending on thedesired strength, as long as they can provide adhesive strength withsufficient conductivity following processing.

FIG. 3 is a flow diagram of an alternative process for transferlamination of electrodes, in accordance with an example embodiment ofthe disclosure. This process comprises physically mixing electrodeactive material, conductive additive, and binder together coupled withpyrolysis and transfer lamination processes.

This process is shown in the flow diagram of FIG. 3, starting with step301 where the active material may be mixed with a binder/resin such aspolyimide (PI) or polyamide-imide (PAI), solvent, the silosilazaneadditive, and optionally a conductive carbon. For example, graphene/VGCF(1:1 by weight) may be dispersed in NMP under sonication for, e.g.,45-75 minutes followed by the addition of Super P (1:1:1 with VGCF andgraphene) and additional sonication for, e.g., 1 hour. Silicon powderwith a desired particle size, may then be dispersed in polyamic acidresin (10-20% solids in N-Methyl pyrrolidone (NMP)) at, e.g., 800-1200rpm in a ball miller for a designated time, and then the conjugatedcarbon/NMP slurry may be added and dispersed at, e.g., 1800-2200 rpmfor, e.g., another predefined time to achieve a slurry viscosity within2000-4000 cP and a total solid content of about 30%. The particle sizeand mixing times may be varied to configure the active material densityand/or roughness.

In step 303, the slurry may be coated on a substrate, such as copper,titanium, chromium, graphite, nickel, stainless steel, tungsten, etc.The slurry may be coated on the substrate film at a loading of 1.5-5mg/cm² (with 15% solvent content), and then dried to remove a portion ofthe solvent in step 305. An optional calendering process may be utilizedwhere a series of hard pressure rollers may be used to finish thefilm/substrate into a smoothed and denser sheet of material.

The coating may be followed by a cure and pyrolysis step 307, where thefilm may be thermally treated (optionally after drying it first) at500-1300° C. to convert the polymer matrix into carbon. The pyrolysisstep may result in an anode active material having silicon contentgreater than or equal to 50% by weight, where the anode has beensubjected to heating at or above 400 degrees Celsius.

In step 309, the pyrolyzed material may be transfer laminated from thesubstrate on the current collector (e.g., using flat press or rollpress), where a copper foil may be coated with polyamide-imide with anominal loading of 0.35-0.75 mg/cm² (applied as a 5-7 wt % varnish inNMP, dried 10-20 hour at 100-140° C. under vacuum). In flat presslamination, the silicon-carbon composite film may be laminated to thecoated copper using a heated hydraulic press (30-70 seconds, 250-350°C., and 3000-5000 psi), thereby forming the finished silicon-compositeelectrode. In another embodiment, the pyrolyzed material may beroll-press laminated to the current collector.

In step 311, the electrode may then be sandwiched with a separator andcathode with electrolyte to form a cell. The cell may be subjected to aformation process, comprising initial charge and discharge steps tolithiate the anode, with some residual lithium remaining. In someinstances, expansion of the anode may be measured to confirm reducedexpansion and anisotropic nature of the expansion. The larger siliconparticle size results in a rougher surface, higher porosity and lessdense material, which reduces the expansion of the active materialduring lithiation.

FIG. 4 illustrates roll press and flat press of anode active material,in accordance with an example embodiment of the disclosure. Referring toFIG. 4, there is shown roll press lamination 410 and flat presslamination 420.

In roll press lamination 410, a current collector 401 and activematerial 405 may be roll pressed using a pair of rollers 407. Thecurrent collector 401 and the active material 405 may be similar to thecurrent collector 201 and active material 205 described with respect toFIG. 2. The rollers 407 may comprise rigid cylindrical structures forapplying a configurable pressure to material passed between them in alamination process. Further, heat may be applied to the materials beinglaminated, such as using heating elements in the rollers 407 (as shownin FIG. 4), or from external heat sources.

In flat press lamination 420, flat surfaces are pressed together toapply pressure to the electrode layers. The roll press laminationprocess thus has variables of pressure and temperature.

It should be noted that while FIG. 4 shows active material on one side,the disclosure is not so limited, as the roll press process applies todouble-sided foils too. An example of such implementation is shown inFIG. 5.

In some instances, scaling electrode production may be desirable.Electrode processing solutions that allow for continuous and speedymanufacturing may be particularly suitable for facilitating high volumeelectrode production. For example, roll press may be used, as it may beparticularly suitable for continuous and speedy processing, as describedbelow.

FIG. 5 illustrates an example system for double-sided roll press ofanode active material, in accordance with an example embodiment of thedisclosure. Shown in FIG. 5 is a roll-to-roll system 500 configured fordouble-sided roll press lamination.

In this regard, as shown in FIG. 5, two rolls may be used to feed twoseparate single-side coated and pyrolyzed electrode composite materialfilms on corresponding carriers 503, which are then rolled processed onthe two sides of a current collector 501 using pair of rollers 507. Therollers 507 may be substantially similar to the rollers 407, but may beconfigured for supporting double-sided press roll. In this regard, thecurrent collector 501 is fed in between and lined up with the pyrolyzedelectrode composite material films on carriers 503 through the rollers507, which may rotate in opposite directions (as shown in FIG. 5).

As the lined up composite material films 503 and the current collector501 pass through the rollers 507, the composite material films arepeeled off or detached from the carrier films 509, and attached (i.e.,laminated) to both sides of the current collector 501, resulting indouble-sided laminated electrode 511. The carrier films 509 may berolled and reused.

In some instances, scaling electrode production may be desirable.Accordingly, various implementations in accordance with the presentdisclosure provide processes and corresponding apparatuses configuredfor high volume electrode production, particularly being configured forprocessing silicon-dominant anodes, based on carbonized polymer as themechanical structure, in continuous electrode form.

In this regard, the mechanical integrity of the electrode web may bemaintained during the entire process. In order to maximize performanceof the silicon-dominant anode based on conversion into carbon of apolymer matrix, complete carbonization of the polymer (requires >500° C.temperature), good cohesion of the active material film, and goodadhesion of the active material film to the current collector should beachieved. Examples of such processes and/or corresponding systems aredescribed with respect to FIG. 6-11.

FIG. 6 illustrates an example high volume roll-to-roll electrodelamination based system, in accordance with an example embodiment of thedisclosure. Shown in FIG. 6 is system 600, which may be used for highvolume roll-to-roll electrode lamination.

In this regard, an example process for providing high volume electrodelamination (as implemented in FIG. 6) may include coating an electrodemixture, comprising active material and polymer, onto a substrate andsubmit the resulting assembly to heat-treatment/pyrolysis (e.g., atemperature >500° C., in an inert or reducing atmosphere). This resultsin an active material film deposited on the substrate with a weakadhesion. The material that can be used as a substrate (also referred toas carrier film) for the heat treatment process are copper, titanium,chromium, graphite, or nickel. The active material film is thentransferred from the original substrate to an adhesive coated currentcollector (e.g., a copper foil) by a lamination process at a configuredtemperature and pressure. The entire process can be conducted as roll toroll, in similar manner as described with respect to FIG. 5.

For example, in the implementation illustrated in FIG. 6, a mixture ofactive material and binder/resin/polymer (referred to as “precursorcomposite film”) may initially be coated onto a substrate (e.g., carrierfilm) 610, with a weak adhesion, and go through drying and curing stagesto form a precursor composite film 601 on carrier film 610. The carrierfilm 610 may be a metal film made from metals such as copper, titanium,chromium, graphite, nickel, stainless steel, tungsten, etc. Thedisclosure is not limited to metal based carrier films, however, andother types may be used. For example, in some embodiments, a carrierfilm may be a ceramic film, a carbon or carbide-based film, or may bemade of a glass, quartz, or silica product.

The precursor composite film 601 on film 610 is fed through a heat treat(pyrolysis) oven 602, and the precursor composite film is pyrolyzed onthe carrier film as it moves through the heat treat oven 602, to convertthe precursor to carbon, resulting in a pyrolyzed composite film 609 onthe carrier film 610. In this regard, the pyrolysis may be conducted attemperature >500° C., in a reducing atmosphere. For example, an inertatmosphere, a vacuum and/or flowing argon, nitrogen, or helium gas maybe used.

In some embodiments, precursor composite films on two carrier films maygo through the system 600 simultaneously, including being pyrolyzed atthe same time in the same or different heat treat oven(s). In theimplementation shown in FIG. 6, the same oven is used for two precursorcomposite films on two carrier films, whereas FIG. 7 illustrates animplementation with two different ovens.

Following the pyrolysis step, two carrier films 610, the pyrolyzedcomposite films 609 on them, may go through a set of rollers 603 thatput a space between the two carrier films 610, allowing a currentcollector 604 to be introduced to the system 600. The current collector604 is fed in between and lined up with the pyrolyzed composite materialfilms 611 on the two carrier film lines 610 through a set of rollers605, which are similar to the rollers 507 of FIG. 5.

Thus, the rollers 605 perform roll-to-roll lamination press atconfigured temperature and pressure as the lined up pyrolyzed compositefilms 609 and the current collector 604 pass through them. In thisregard, the pyrolyzed composite films 609 are peeled off or detachedfrom the carrier films 610, and attached (i.e., laminated) to both sidesof the current collector 604, resulting in double-sided compositeelectrode film 611.

Optionally, the composite electrode film 611 (comprising the pyrolyzedcomposite material films 609 attached to both sides of the currentcollector 604) may be cleaned and inspected as they go through a cleanand inspection station 607. The composite electrode film 611 may then berolled up into an electrode roll 608 for making batteries.

In some embodiments, the length of heat treat oven 602 may be about 12 mto about 18 m, preferably about 14 m, and the amount of time a specificlocation on the film stays in the heat treat oven may be about 1 min toabout 40 min, about 1.5 min to about 30 min, about 1.2 min to about 6min, preferably about 1.5 min. The heat treat speed and the laminationspeed are about 1 m/min to about 100 m/min, about 8 m/min to about 12m/min, preferably about 10 m/min.

FIG. 7 illustrates another example high volume roll-to-roll electrodelamination based system, in accordance with an example embodiment of thedisclosure. Shown in FIG. 7 is system 700, which may be used for highvolume roll-to-roll electrode lamination. The system 700 issubstantially similar to the system 600 described with respect to FIG.6. The system 700 uses, however, multiple pyrolysis ovens.

For example, in the implementation illustrated in FIG. 7, two precursorcomposite films 701 (similar to the precursor composite films 601 ofFIG. 6) on carrier films 710 (similar to the carrier films 610 of FIG.6) are fed through two separate heat treat (pyrolysis) ovens 702 (eachof which is similar the oven 602 of FIG. 6), and the precursor compositefilms are separately pyrolyzed on the carrier films as they move throughthe heat treat ovens 702. The pyrolysis is performed in similar manneras described with respect to FIG. 6.

Following the pyrolysis step, two carrier films 710, the pyrolyzedcomposite films 709 on them, may go through a set of rollers 703 thatput a space between the two carrier films 710, allowing a currentcollector 704 to be introduced to the system 700. The current collector704 is fed in between and lined up with the pyrolyzed composite materialfilms 709 on the two carrier film lines 710 through a set of rollers705, which are similar to the rollers 507 of FIG. 5. Thus, the rollers705 perform roll-to-roll lamination press at configured temperature andpressure as the lined up pyrolyzed composite films 709 and the currentcollector 704 pass through them. In this regard, the pyrolyzed compositefilms 709 are peeled off or detached from the carrier films 710, andattached (i.e., laminated) to both sides of the current collector 704,resulting in double-sided composite electrode film 711.

The composite electrode film 711 (comprising the pyrolyzed compositematerial films 709 attached to both sides of the current collector 704)may be cleaned and inspected via the clean and inspection station 707.The composite electrode film 711 may then be rolled up into an electroderoll 708 for making batteries.

FIG. 8 illustrates a top view of an example roll-to-roll system withmultiple manufacturing lanes, in accordance with an example embodimentof the disclosure. Shown in FIG. 8 is system 800, which may be used forhigh volume roll-to-roll electrode lamination using manufacturing lanes.

In this regard, in some embodiments, to further increase volumes,multiple lanes of manufacturing lines may be set up or used in alamination based system, such as to simultaneously produce multiplecomposite electrode rolls. For example, as shown in FIG. 8, such systemmay incorporate four lanes, each based on a single-lane implementation,such as one similar to the system shown in FIG. 6 or FIG. 7. In someinstances, however, some of the components may be combined (or a singlecomponent may be used for all of the manufacturing lanes).

For example, as shown in FIG. 8, the system 800 may use 8 separate rollsfeeding 4 pairs of precursor composite films 801 (similar to theprecursor composite films 601 and 701 of FIGS. 6 and 7) on 8corresponding carrier films (each similar to the carrier films 610 and710 of FIGS. 6 and 7). In this regard, as the top view of the system isshown in FIG. 8, only the top film in each lane is shown. A single oven802, which may be substantially similar to the ovens films 602 and 702of FIGS. 6 and 7 (but configured for, e.g., applying pyrolysis to 8different films) is then used to heat treat all of the precursorcomposite films 801, resulting in 8 corresponding pyrolyzed films 809(similar to the pyrolyzed films 609 and 709 of FIGS. 6 and 7).

The pyrolyzed films 809 are then moved using rollers 803 (similar topyrolyzed films 603 and 703 of FIGS. 6 and 7), which may also createspace to allow introducing 4 corresponding current collectors (notshown), and these components are then pressed via rollers 805 (similarto rollers 605 and 705 of FIGS. 6 and 7) to create 4 correspondingdouble-sided composite electrode films 811 (similar to electrode films611 and 711 of FIGS. 6 and 7), each comprising two pyrolyzed compositematerial films 809 attached to both sides of the current collector 704.

The composite electrode films 811 (comprising the pyrolyzed compositematerial films 809 attached to both sides of the current collectors) maybe cleaned and inspected via 4 corresponding clean and inspectionstations 807 (similar to electrode stations 607 and 707 of FIGS. 6 and7). The composite electrode films 811 may then be rolled up into 4individual electrode rolls 808.

While not specifically shown in FIGS. 6-9, the systems illustrated anddescribed therein include components (e.g., hardware components,circuitry, etc.) for supporting various functions performed in thesesystems. The systems may incorporate, for example, suitable components(e.g., sensors, control circuitry, etc., not shown) for providingsensory and control functions for monitoring operations of the systems.The systems may also incorporate input/output subsystems (e.g., inputdevices, output devices, circuitry, etc.) for supporting and/orfacilitating user interactions with the systems.

To ensure quality of electrodes produced using high volume roll-to-rolllamination based processes, cells incorporating such electrodes andperformance thereof may be compared against baseline cells—e.g., cellsproduced using baseline process, such as continuous batch process. Inthis regard, the baseline process includes forming a precursor compositefilm on a carrier film, peeling the precursor composite film off thecarrier, cutting the precursor composite film into appropriate size foran electrode, pyrolyzing the cut precursor composite film pieces, andthen placing the pyrolyzed pieces on both sides of a copper foil coatedwith a layer of polyamide-imide (PAI).

For example, with respect to cell energy density, the cell energydensities of cells produced using electrodes made by high volumeroll-to-roll lamination based processes compare favorably to cellsincorporating electrode made by baseline continuous batch process. Thisis illustrated in Table 1, which shows example energy densities of 5 Lcells, and Table 2, which shows example modeled energy densities of anEV cell (550×100 mm):

TABLE 1 Baseline continuous Roll-to-roll transfer batch processlamination process 4.2 V-2.75 V (0% SOC) 598 Wh/L 598-639 Wh/L 4.2V-2.75 V (100% SOC) 556 Wh/L 556-598 Wh/L

TABLE 2 Baseline continuous Roll-to-roll transfer batch processlamination process 4.2 V-2.75 V (0% SOC) 984 Wh/L 984-1022 Wh/L 4.2V-2.75 V (100% SOC) 911 Wh/L 911-946 Wh/L

FIG. 9 illustrates a top view of an embodiment of an electrode roll withmultiple mixture strips on a single current collector, in accordancewith an example embodiment of the disclosure.

In this regard, in some embodiments, a roll-to-roll system may beconfigured for making electrode rolls with multiple mixture strips on asingle current collector. This may be done by use of multiplemanufacturing lines, each being configured for roll-on-roll laminatedbased electrode processing—e.g., being similar to one of the systemsshown in FIG. 6 and FIG. 7. Alternatively, a roll-on-roll system such asthose illustrated in FIGS. 6 and 7 may be modified to support processingof multiple-strip rolls—e.g., where the precursor composite film oncarrier film has multiple strips of precursor composite, and with thesystem being configured to process the film such that the final productwould have multiple strips in the electrode roll.

For example, as shown in FIG. 9, three strips of the mixture may becoated on the carrier or the current collector 902. After going throughdrying and curing, three strips of precursor composite films are presenton the carrier or the current collector 902. The width of the carrier orthe current collector may be about 300 mm to about 3200 mm, about 1300mm to about 3200 mm. The width 903 a of the coated mixture may bebetween about 300 mm to about 800 mm, preferably about 550 mm to about555 mm, and the distance 903 b between each strip of coated mixture maybe between about 10 mm to about 60 mm, preferably about 15 mm. Thecoating speed for coating the mixture onto the carrier or the currentcollection may be between about 60 m/minute to about 100 m/minute,preferably 80 m/minutes.

FIG. 10 is a plot illustrating cycle life performance for cells that useelectrodes produced using high-volume lamination based roll-to-rollprocess, in accordance with an example embodiment of the disclosure.

The plot shown FIG. 10 compares capacity retention, as a measure ofcycle life performance, for cells corresponding to two different groups:group 1001 and group 1003. In this regard, group 1001 representsbaseline cells—that is, cells produced using continuous batch process;whereas group 1003 represents cells incorporating electrodes producedusing lamination based roll-to-roll process. The capacity retention forboth cell groups is measured under 0.5 C charge to 4.2V and 0.5 Cdischarge to 3.3V (4.2V-3.3V(0.5 C/0.5 C)) test conditions. As shown inthe plot in FIG. 11, cells with electrodes made using high volumelamination based roll-to-roll process exhibit comparable cycle life(capacity retention) performance as baseline cells.

FIG. 11 is a plot illustrating cell thickness expansion performance forcells that use electrodes produced using high-volume lamination basedroll-to-roll process, in accordance with an example embodiment of thedisclosure.

The plot shown FIG. 11 compares cell expansion, as measure of cellperformance, for cells corresponding to two different groups: group 1101and group 1103. In this regard, group 1101 represents baselinecells—that is, cells produced using continuous batch process; whereasgroup 1103 represents cells incorporating electrodes produced usinglamination based roll-to-roll process. The cell expansion for both cellgroups is measured based on changes in cell thickness against number ofcharge/discharge cycles. As shown in the chart in FIG. 11, cells withelectrodes made using high volume lamination based roll-to-roll processexhibit comparable or better cell expansion compared to baseline cells.

An example system for continuous roll-to-roll electrode processing, inaccordance with the present disclosure, comprises a plurality of carrierfilms, wherein each carrier film has applied thereon at a start ofelectrode processing in the system, at least one precursor compositefilm; one or more heat treatment ovens, wherein each heat treatment ovenis configured for applying pyrolysis to at least one carrier film, toconvert a corresponding precursor composite film on the carrier film toa pyrolyzed composite film; and a plurality of press rollers, wherein atleast two of the plurality of press rollers are configured for pressingonto two sides of a current collector film, two pyrolyzed mixture filmsfrom two corresponding carrier films, to create a correspondingelectrode composite film, wherein the two corresponding carrier filmsare separated after the pressing.

In an example embodiment, the at least one precursor composite filmcomprises silicon (Si).

In an example embodiment, the system further comprises a plurality ofmoving rollers, configured for moving the plurality of carrier filmsduring the electrode processing in the system.

In an example embodiment, each heat treatment oven is configured toapply the pyrolysis at temperature >500° C.

In an example embodiment, each heat treatment oven is configured toapply the pyrolysis in reducing atmosphere.

In an example embodiment, each heat treatment oven is configured tocreate reducing atmosphere related conditions, the reducing atmosphererelated conditions comprising at least one of inert atmosphere, avacuum, flowing of one or more reducing gases.

In an example embodiment, the system further comprises at least onecleaning and inspection component configured for cleaning and inspectingelectrode composite films after pressing.

In an example embodiment, the plurality of press rollers is configuredto apply one or both of pressure and heat during the pressing.

In an example embodiment, each heat treatment oven is configured forapplying pyrolysis to only one carrier film.

An method for electrode processing in a roll-to-roll system, inaccordance with the present disclosure, comprises applying to each of aplurality of carrier films, at least one precursor composite film;applying pyrolysis to each of the plurality of carrier films, whereinthe pyrolysis is configured for converting a corresponding precursorcomposite film on each carrier film to a pyrolyzed composite film; rollpressing onto two sides of a current collector film, two pyrolyzedmixture films from two corresponding carrier films, to create anelectrode composite film; and separating the two corresponding carrierfilms after the pressing.

In an example embodiment, the method further comprises moving theplurality of carrier films during the electrode processing in the systemusing a plurality of moving rollers, configured for.

In an example embodiment, the method further comprises applying thepyrolysis at temperature >500° C.

In an example embodiment, the method further comprises applying thepyrolysis in a reducing atmosphere.

In an example embodiment, the method further comprises creating reducingatmosphere related conditions during the pyrolysis, the reducingatmosphere related conditions comprising at least one of inertatmosphere, a vacuum, flowing of one or more reducing gases.

In an example embodiment, the method further comprises cleaning andinspecting each electrode composite film after pressing.

In an example embodiment, the roll pressing comprises applying one orboth of pressure and heat during the pressing.

In an example embodiment, the at least one precursor composite filmcomprises silicon (Si).

As utilized herein, “and/or” means any one or more of the items in thelist joined by “and/or”. As an example, “x and/or y” means any elementof the three-element set {(x), (y), (x, y)}. In other words, “x and/ory” means “one or both of x and y.” As another example, “x, y, and/or z”means any element of the seven-element set {(x), (y), (z), (x, y), (x,z), (y, z), (x, y, z)}. In other words, “x, y and/or z” means “one ormore of x, y, and z.” As utilized herein, the term “exemplary” meansserving as a non-limiting example, instance, or illustration. Asutilized herein, the terms “for example” and “e.g.” set off lists of oneor more non-limiting examples, instances, or illustrations.

As utilized herein the terms “circuits” and “circuitry” refer tophysical electronic components (e.g., hardware), and any software and/orfirmware (“code”) that may configure the hardware, be executed by thehardware, and or otherwise be associated with the hardware. As usedherein, for example, a particular processor and memory (e.g., a volatileor non-volatile memory device, a general computer-readable medium, etc.)may comprise a first “circuit” when executing a first one or more linesof code and may comprise a second “circuit” when executing a second oneor more lines of code. Additionally, a circuit may comprise analogand/or digital circuitry. Such circuitry may, for example, operate onanalog and/or digital signals. It should be understood that a circuitmay be in a single device or chip, on a single motherboard, in a singlechassis, in a plurality of enclosures at a single geographical location,in a plurality of enclosures distributed over a plurality ofgeographical locations, etc. Similarly, the term “module” may, forexample, refer to a physical electronic components (e.g., hardware) andany software and/or firmware (“code”) that may configure the hardware,be executed by the hardware, and or otherwise be associated with thehardware.

As utilized herein, circuitry or module is “operable” to perform afunction whenever the circuitry or module comprises the necessaryhardware and code (if any is necessary) to perform the function,regardless of whether performance of the function is disabled or notenabled (e.g., by a user-configurable setting, factory trim, etc.).

Other embodiments of the invention may provide a non-transitory computerreadable medium and/or storage medium, and/or a non-transitory machinereadable medium and/or storage medium, having stored thereon, a machinecode and/or a computer program having at least one code sectionexecutable by a machine and/or a computer, thereby causing the machineand/or computer to perform the processes as described herein.

Accordingly, various embodiments in accordance with the presentinvention may be realized in hardware, software, or a combination ofhardware and software. The present invention may be realized in acentralized fashion in at least one computing system, or in adistributed fashion where different elements are spread across severalinterconnected computing systems. Any kind of computing system or otherapparatus adapted for carrying out the methods described herein issuited. A typical combination of hardware and software may be ageneral-purpose computing system with a program or other code that, whenbeing loaded and executed, controls the computing system such that itcarries out the methods described herein. Another typical implementationmay comprise an application specific integrated circuit or chip.

Various embodiments in accordance with the present invention may also beembedded in a computer program product, which comprises all the featuresenabling the implementation of the methods described herein, and whichwhen loaded in a computer system is able to carry out these methods.Computer program in the present context means any expression, in anylanguage, code or notation, of a set of instructions intended to cause asystem having an information processing capability to perform aparticular function either directly or after either or both of thefollowing: a) conversion to another language, code or notation; b)reproduction in a different material form.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

What is claimed is:
 1. A method for electrode processing in aroll-to-roll system, the method comprising: applying to each of aplurality of carrier films, at least one precursor composite film;applying pyrolysis to each of the plurality of carrier films, whereinthe pyrolysis is configured for converting a corresponding precursorcomposite film on each carrier film to a pyrolyzed composite film; androll pressing onto two sides of a current collector film, two pyrolyzedmixture films from two corresponding carrier films, to create anelectrode composite film.
 2. The method of claim 1, comprisingseparating the two corresponding different carrier films of theplurality of carrier films after the pressing.
 3. The method of claim 1,comprising moving the plurality of carrier films during the electrodeprocessing in the system using a plurality of moving rollers.
 4. Themethod of claim 1, comprising applying the pyrolysis at a temperatureof >500° C.
 5. The method of claim 1, comprising applying the pyrolysisin a reducing atmosphere.
 6. The method of claim 5, comprising creatingreducing atmosphere related conditions during the pyrolysis, thereducing atmosphere related conditions comprising at least one of aninert atmosphere, a vacuum, or flowing of one or more reducing gases. 7.The method of claim 1, comprising cleaning and inspecting each electrodecomposite film after pressing.
 8. The method of claim 1, wherein theroll pressing comprises applying one or both of pressure and heat duringthe pressing.
 9. The method of claim 1, wherein the at least oneprecursor composite film comprises silicon (Si).